The devices at present used in odontological field for the removal of wastes in the oral cavity and particularly in the dental cavity comprise an air-water spray violently moving the wastes away by projection thereof also out of the cavity in the surrounding environment, and an aspirator which by operating separately and in successive times removes the solid and liquid residual wastes. Such devices suffer from the following disadvantages: the violent spray action, by outwardly projecting fragments or pieces of dentine, of bacterial plaque, causes a serious pollution or contamination by spreading in the surrounding environment corpuscules and powders of high bacterial charge. The action of the aspirator acting separately and in successive times is limited to collect the remaining solid and liquid material in the oral cavity without avoiding the scattering of the above mentioned material. It is the object of the present invention to overcome such disadvantages.